Microwave single-photon detector and method

Abstract

The application discloses a kind of micro-wave single-photon detectors and methods.Therein, the detector includes: metal cavity cavity, including first resonant cavity and second resonant cavity, one side of first resonant cavity is equipped with first probe, one side of second resonant cavity is equipped with second probe and third probe, second probe is connected with the control reading signal input port of micro-wave single-photon detector, third probe is connected with the control reading signal output port of micro-wave single-photon detector;Multi-port device, the first port of multi-port device is connected with the micro-wave single-photon input port of micro-wave single-photon detector, the second port of multi-port device is connected with first probe, the third port of multi-port device is connected with first probe and is connected with the micro-wave single-photon output port of micro-wave single-photon detector;Superconducting quantum bits, traverse first resonant cavity and second resonant cavity.The application solves the technical problem of poor detection effect of micro-wave single-photon detection in the related art.

Description

Technical Field

[0001] This invention relates to the field of optics, and more specifically, to a microwave single-photon detector and method. Background Technology

[0002] A single-photon detector is an ultrasensitive detector capable of detecting a single photon—the smallest unit of energy in light. It is widely used in fields such as biofluorescence detection, DNA sequencing, medical imaging, molecular spectroscopy, lidar, and quantum information. In the field of superconducting quantum computing, microwave-band single-photon detectors have particularly important applications, serving as crucial components in long-distance quantum entanglement, distributed quantum computing, and quantum networks.

[0003] There is currently no effective solution to the above problems. Summary of the Invention

[0004] This invention provides a microwave single-photon detector and method to at least solve the technical problem of poor detection performance in microwave single-photon detection in related technologies.

[0005] According to one aspect of the present invention, a microwave single-photon detector is provided, comprising: a metal cavity including a first resonant cavity and a second resonant cavity, a first probe being mounted on one side of the first resonant cavity, and a second probe and a third probe being mounted on one side of the second resonant cavity, the second probe being connected to a control readout signal input port of the microwave single-photon detector, and the third probe being connected to a control readout signal output port of the microwave single-photon detector; a multi-port device, a first port of the multi-port device being connected to the microwave single-photon input port of the microwave single-photon detector, a second port of the multi-port device being connected to the first probe, and a third port of the multi-port device being connected to the microwave single-photon output port of the microwave single-photon detector; and a superconducting quantum bit traversing the first resonant cavity and the second resonant cavity.

[0006] Alternatively, the superconducting quantum bit consists of a planar capacitor and a Josephson junction.

[0007] Optionally, the parallel plate capacitor is formed by fabricating a thin film of superconducting material, and the Josephson junction is a Josephson junction with a three-layer structure of superconductor-insulator-superconductor.

[0008] Optionally, the superconducting quantum bits are coupled to the first resonant cavity and the second resonant cavity respectively through a planar capacitor.

[0009] Optionally, the microwave single-photon detector further includes: a substrate, traversing the first and second resonant cavities, with superconducting qubits disposed on the substrate.

[0010] Optionally, the substrate can be a silicon wafer or a sapphire wafer.

[0011] Optionally, the resonant frequency of the first resonant cavity is less than the resonant frequency of the second resonant cavity.

[0012] Optionally, the second probe penetrates into the second resonant cavity by a shorter length than the third probe penetrates into the second resonant cavity.

[0013] Optionally, the ambient temperature of the microwave single-photon detector is lower than a preset temperature.

[0014] According to another aspect of the present invention, a microwave single-photon detection method is also provided. The method is applied to the microwave single-photon detector of any of the above-mentioned embodiments. The method includes: applying a first control signal through a control readout signal input port, wherein the first control signal is used to control the quantum state of the superconducting qubit to change from the ground state to a first superposition state; inputting a microwave single photon through a microwave single-photon input port; and detecting the microwave single photon through a microwave single-photon output port.

[0015] Optionally, applying a first control signal by controlling the read signal input port includes: applying a first microwave pulse signal by controlling the read signal input port; reading the first amplitude and first phase of the first microwave pulse signal by controlling the read signal output port; determining the first quantum state of the superconducting quantum bit based on the first amplitude and first phase; and applying the first control signal by controlling the read signal input port in response to the first quantum state being the ground state.

[0016] Optionally, after detecting the microwave single photon through the microwave single photon output port, the method further includes: applying a second control signal through a control readout signal input port, wherein the second control signal is used to control the quantum state of the superconducting qubit to change to a second quantum state; applying a second microwave pulse signal through the control readout signal input port; reading the second amplitude and second phase of the second microwave pulse signal through the control readout signal output port; determining the second quantum state of the superconducting qubit based on the second amplitude and second phase; and determining whether a microwave single photon is input to the microwave single photon input port based on the second quantum state.

[0017] Optionally, determining whether a microwave single-photon input port receives a microwave single photon based on the second quantum state includes: determining that no microwave single photon is received at the microwave single-photon input port in response to the second quantum state being the ground state; and determining that a microwave single photon is received at the microwave single-photon input port in response to the second quantum state being the excited state.

[0018] According to another aspect of the present invention, a computer-readable storage medium is also provided, the computer-readable storage medium including a stored program, wherein, when the program is executed, it controls the device where the computer-readable storage medium is located to execute the microwave single-photon detection method of the above-described method embodiments.

[0019] According to another aspect of the present invention, a processor is also provided, which is used to run a program, wherein the program executes the microwave single-photon detection method of the above-described method embodiments.

[0020] In this embodiment of the invention, the microwave single-photon detector may include a metal cavity with two resonant cavities, a multi-port device for connecting multiple ports of the detector to the resonant cavities, and a superconducting quantum bit traversing the two resonant cavities. By using a dual-resonant-cavity structure to separate the input resonant cavity of the microwave single photon and the control and readout resonant cavity of the superconducting quantum bit, it is possible to avoid residual microwave signals for control and readout within the input resonant cavity of the microwave single photon, thereby reducing the dark count of the microwave single-photon detector. At the same time, using a superconducting quantum bit with a fixed frequency also reduces the interference of magnetic flux noise in the environment on the microwave single-photon detection, improves the phase decoherence time of the superconducting quantum bit, thereby improving the detection efficiency of the microwave single-photon detector, and thus solving the technical problem of poor detection effect of microwave single-photon detection in related technologies. Attached Figure Description

[0021] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0022] Figure 1 This is a schematic diagram of the structure of a microwave single-photon detector according to an embodiment of the present invention;

[0023] Figure 2 This is a schematic diagram of the structure of a superconducting quantum bit shown in an embodiment of this application and disclosure;

[0024] Figure 3a This is a structural diagram of the upper half of the interior of the metal cavity shown in this embodiment;

[0025] Figure 3b This is a structural diagram of the lower half of the interior of the metal cavity from a first perspective, as shown in this embodiment.

[0026] Figure 3c This is a structural diagram of the lower half of the interior of the metal cavity from a second perspective, as shown in this embodiment.

[0027] Figure 4 This is a flowchart illustrating a microwave single-photon detection method according to this embodiment. Detailed Implementation

[0028] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0029] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0030] Example 1

[0031] Most mainstream microwave single-photon detectors currently utilize the interaction between superconducting qubits and microwave photons, detecting microwave single photons by detecting the quantum state of the superconducting qubits.

[0032] To meet the application requirements of quantum information, such as the need for non-destructive detection of microwave photons by microwave single-photon detectors, meaning that the photon still exists after being detected, a phase control gate can generally be constructed between the microwave photon and the superconducting qubit. Then, the presence of a microwave single photon can be determined by detecting the phase change of the superconducting qubit, thereby avoiding disturbance to the photon count. Currently, there are two main methods for detecting microwave single photons using a control phase gate: The first method uses a superconducting qubit with a fixed coupling frequency in a single resonant cavity for detection. However, because the microwave single photon input resonant cavity and the control and readout resonant cavity of the superconducting qubit overlap, the microwave control and readout signals may remain in the resonant cavity. This results in a high dark count for the microwave single photon detector, leading to inaccurate detection results. The second method uses a superconducting qubit with a tunable coupling frequency in a dual resonant cavity for detection. This method typically utilizes the tunable frequency characteristics of the superconducting qubit to construct a control phase gate between the microwave photon and the superconducting qubit. However, tunable superconducting qubits are very sensitive to stinging noise, and their energy level transition frequencies are easily disturbed, leading to a decrease in the phase dephasing time of the superconducting qubit. This, in turn, affects the detection efficiency of the microwave single photon detector, resulting in lower detection efficiency.

[0033] To address the aforementioned problems, according to an embodiment of the present invention, a device embodiment for a microwave single-photon detector is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0034] Figure 1 This is a schematic diagram of the structure of a microwave single-photon detector according to an embodiment of the present invention, as shown below. Figure 1 As shown, the detector may include the following components: a metal cavity 102, a multi-port device 104 and a superconducting quantum bit 106, a first resonant cavity 1021, a second resonant cavity 1022, a microwave single-photon input port 108 of the microwave single-photon detector, a microwave single-photon output port 110 of the microwave single-photon detector, a control readout signal input port 112 of the microwave single-photon detector, and a control readout signal output port 114 of the microwave single-photon detector.

[0035] The metal cavity 102 includes a first resonant cavity and a second resonant cavity. A first probe is mounted on one side of the first resonant cavity, and a second probe and a third probe are mounted on one side of the second resonant cavity. The second probe is connected to the control readout signal input port of the microwave single-photon detector, and the third probe is connected to the control readout signal output port of the microwave single-photon detector.

[0036] The aforementioned metal cavity can refer to a hollow metal cavity capable of continuously oscillating a high-frequency electromagnetic field within it, such as an aluminum alloy cavity or a copper-zinc alloy cavity. Considering the detection effect on microwave single photons, high-purity aluminum can be used to fabricate the aforementioned metal cavity.

[0037] The first resonant cavity mentioned above may refer to the aforementioned microwave single-photon input resonant cavity.

[0038] The aforementioned second resonant cavity may refer to the control and readout resonant cavity of the superconducting quantum bit.

[0039] To avoid the overlap between the microwave single-photon input resonant cavity and the superconducting quantum bit control and readout resonant cavity, which would increase the dark count of the microwave single-photon detector, a dual-cavity structure can be adopted. The aforementioned metal cavity is divided into upper and lower parts. One part serves as the microwave single-photon input resonant cavity, i.e., the first resonant cavity, and the other part serves as the superconducting quantum bit control and readout resonant cavity, i.e., the second resonant cavity.

[0040] Generally, probes corresponding to their functions can be arranged on the cavity wall on one side of the resonant cavity. In one optional scheme of this embodiment, considering that the first resonant cavity can be used as an input resonant cavity for microwave single photons, a hole can be drilled in the cavity wall on one side of the first resonant cavity and a first probe can be assembled there. Considering that the second resonant cavity can be used as a control and readout resonant cavity for superconducting qubits, a hole can be drilled in the cavity wall on one side of the second resonant cavity and a second probe and a third probe can be assembled there.

[0041] In one optional embodiment, the second probe can be connected to the control readout signal input port of the microwave single-photon detector, and the third probe can be connected to the control readout signal output port of the microwave single-photon detector.

[0042] The multi-port device 104 has a first port connected to the microwave single-photon input port of the microwave single-photon detector, a second port connected to the first probe, and a third port connected to the microwave single-photon output port of the microwave single-photon detector.

[0043] The aforementioned multi-port device can refer to a device used to transmit incident waves from any port to the next port in a direction sequence determined by the static deflection magnetic field.

[0044] In one alternative embodiment, considering the efficiency of signal transmission, a circulator can be selected as the aforementioned multi-port device.

[0045] In one optional embodiment, the first port of the multi-port device can be connected to the microwave single-photon input port of the microwave single-photon detector, the second port of the multi-port device can be connected to the first probe of the first resonant cavity, the third port of the multi-port device can be connected to the microwave single-photon output port of the microwave single-photon detector, the control read signal input port can be connected to the second probe of the second resonant cavity, and the control read signal output port can be connected to the third probe of the second resonant cavity.

[0046] 106 superconducting qubits traverse the first and second resonant cavities.

[0047] To improve the detection performance of microwave single-photon detectors, superconducting qubits can be inserted across the first resonant cavity and the second resonant cavity described above.

[0048] In this embodiment of the invention, the microwave single-photon detector may include a metal cavity with two resonant cavities, a multi-port device for connecting multiple ports of the detector to the resonant cavities, and a superconducting quantum bit traversing the two resonant cavities. By using a dual-resonant-cavity structure to separate the input resonant cavity of the microwave single photon and the control and readout resonant cavity of the superconducting quantum bit, it is possible to avoid residual microwave signals for control and readout within the input resonant cavity of the microwave single photon, thereby reducing the dark count of the microwave single-photon detector. At the same time, using a superconducting quantum bit with a fixed frequency also reduces the interference of magnetic flux noise in the environment on the microwave single-photon detection, improves the phase decoherence time of the superconducting quantum bit, thereby improving the detection efficiency of the microwave single-photon detector, and thus solving the technical problem of poor detection effect of microwave single-photon detection in related technologies.

[0049] Alternatively, the superconducting quantum bit consists of a planar capacitor and a Josephson junction.

[0050] In one alternative embodiment, in order to improve the detection efficiency of the microwave single-photon detector, the aforementioned supermassive quantum bit can be composed of two planar capacitors and a Josephson junction.

[0051] Figure 2 This is a schematic diagram of the structure of a superconducting quantum bit shown in an embodiment of this application, as illustrated in the present disclosure. Figure 2 As shown, 201 represents a parallel plate capacitor, and 202 represents a Josephson junction.

[0052] Optionally, the parallel plate capacitor is formed by fabricating a thin film of superconducting material, and the Josephson junction is a Josephson junction with a three-layer structure of superconductor-insulator-superconductor.

[0053] The superconducting materials mentioned above can refer to materials such as aluminum, niobium, and tantalum, but are not limited to these. The superconductor in the Josephson junction mentioned above can be aluminum, and the insulator can be aluminum oxide, but is not limited to these.

[0054] In one alternative embodiment, a superconducting material thin film can be used to prepare the above-mentioned parallel plate capacitor by photolithography or etching process, and the Josephson junction can be prepared by a two-angle evaporation process using aluminum and aluminum oxide in a three-layer structure of aluminum-alumina-alumina.

[0055] Optionally, the superconducting quantum bits are coupled to the first resonant cavity and the second resonant cavity respectively through a planar capacitor.

[0056] In one alternative embodiment, the superconducting quantum bit described above can be coupled to the first resonant cavity and the second resonant cavity via a planar capacitor.

[0057] In one optional embodiment, the transition frequency of the superconducting quantum bit can be set to 8.643 GHz, and the coupling strength between the superconducting quantum bit and the resonant cavity can be set to 186 MHz by setting an appropriate capacitance value for the planar capacitor.

[0058] Optionally, the microwave single-photon detector further includes: a substrate, traversing the first and second resonant cavities, with superconducting qubits disposed on the substrate.

[0059] The aforementioned substrate can refer to the carrier used to hold superconducting qubits.

[0060] In one alternative embodiment, the microwave single-photon detector may further include a substrate that traverses the first and second resonant cavities, and the superconducting qubits described above are fabricated on the substrate using microfabrication techniques.

[0061] Optionally, the substrate can be a silicon wafer or a sapphire wafer.

[0062] In one alternative embodiment, in order to improve the detection efficiency and accuracy of the microwave single-photon detector, a silicon wafer or a sapphire wafer can be used as the substrate.

[0063] To facilitate understanding of the internal structure of the aforementioned microwave single-tube detector, Figure 3a This is a structural diagram of the upper half of the interior of the metal cavity shown in this embodiment; Figure 3b This is a structural diagram of the lower half of the interior of the metal cavity from a first perspective, as shown in this embodiment. Figure 3c This is a structural diagram of the lower half of the interior of the metal cavity from a second perspective, as shown in this embodiment.

[0064] Specifically, 1021 represents the first resonant cavity, 1022 represents the second resonant cavity, 301 represents the substrate, 106 represents the superconducting quantum bit, 302 represents the first probe, 303 represents the second probe, and 304 represents the third probe.

[0065] In one optional embodiment, when assembling the aforementioned metal cavity, the substrate can first be placed in the groove in the middle of the lower half of the cavity. Then, indium wires can be filled into the small holes at the four corners of the substrate and compacted to fix the substrate. Then, the upper part of the cavity can be placed on the lower half of the cavity. Considering that the upper and lower parts of the metal cavity each have a groove and protrusion of matching size, the upper and lower parts can be assembled together very tightly. Finally, the assembly of the metal cavity can be completed by simply fixing the upper and lower parts of the cavity with screws.

[0066] Optionally, the second probe penetrates into the second resonant cavity by a shorter length than the third probe penetrates into the second resonant cavity.

[0067] Since the length of the probe penetrating the cavity is related to the coupling strength of the external transmission line, the longer the probe penetrates, the greater the coupling strength. However, the coupling strength corresponding to the control readout signal input port of the microwave single-photon detector is less than that corresponding to the control readout signal output port. Therefore, in an optional scheme of this embodiment, the second and third probes can be set to different penetration lengths, and the longer probe can be connected to the control readout signal output port, while the shorter probe can be connected to the control readout signal input port.

[0068] For example, if the control readout signal input port of the microwave single-photon detector is connected to the second probe, and the control readout signal output port is connected to the third probe, then the length of the second probe extending into the second resonant cavity can be set to be less than the length of the third probe extending into the second resonant cavity.

[0069] It should be noted that the connection objects of the second and third probes are only related to their respective lengths. The lengths and connection objects of the second and third probes mentioned above are only illustrative examples. The specific connection objects of each probe can be set as appropriate, and are not limited here.

[0070] Optionally, the resonant frequency of the first resonant cavity is less than the resonant frequency of the second resonant cavity.

[0071] In one alternative embodiment, the resonant frequency of the first resonant cavity can be set to 7.5 GHz, and the resonant frequency of the second resonant cavity can be set to 10 GHz.

[0072] In one alternative embodiment, in order to improve the detection power consumption of the microwave photon detector, the lengths by which the three probes penetrate into their respective cavities can be controlled so that the coupling strength between the first resonant cavity and the external transmission line is 3.1MHz.

[0073] Optionally, the ambient temperature of the microwave single-photon detector is lower than a preset temperature.

[0074] In one optional embodiment, in order to ensure the detection performance of the microwave single-photon detector, the microwave single-photon detector or its various structural components can be placed in a preset low-temperature environment, that is, an environment where the ambient temperature is lower than the preset temperature.

[0075] In one optional embodiment, the aforementioned low-temperature environment may refer to an environment with a temperature less than 20 mK.

[0076] Example 2

[0077] According to embodiments of the present invention, a method for microwave single-photon detection is provided. It should be noted that the steps shown in the flowcharts in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowcharts, in some cases, the steps shown or described may be executed in a different order than that presented here. Optionally, the above method can be executed by the microwave single-photon detector provided in Embodiment 1.

[0078] Figure 4 This is a flowchart illustrating a microwave single-photon detection method according to this embodiment, as shown below. Figure 4 As shown, the method includes the following steps:

[0079] Step S402: Apply a first control signal by controlling the read signal input port.

[0080] The first control signal is used to control the quantum state of the superconducting qubit to change from the ground state to the first superposition state.

[0081] The aforementioned first control signal can refer to a signal used to control and change the quantum state of a superconducting quantum bit.

[0082] The ground state mentioned above can refer to the ground state. .

[0083] The first superposition state mentioned above can refer to a superposition state. .

[0084] In an optional embodiment, the microwave single-photon detector can apply the aforementioned first control signal to the Y gate of the superconducting quantum bit by controlling the readout signal input port, so as to change the quantum state of the superconducting quantum bit from the ground state. Become a superposition state .

[0085] In one alternative embodiment, the first control signal can be a Gaussian pulse signal with a length of 10 ns and a frequency equal to the transition frequency of the superconducting quantum bit, such as 8.643 GHz.

[0086] Step S404: Input microwave single photons through the microwave single photon input port.

[0087] After altering the quantum state of the superconducting qubit, within the next time window, a microwave single photon can be input into the microwave single photon detector through the aforementioned microwave single photon input port. It then enters the first resonant cavity through the multi-port device and the first probe, interacting with the superconducting qubit and rotating its quantum state phase, causing the quantum state to shift from a superposition state. Become a superposition state .

[0088] In one alternative embodiment, the length of the time window is 120 ns, the frequency of the detectable microwave single photon is 7.5 GHz, and the bandwidth is less than 3.1 MHz.

[0089] In one optional embodiment, if no microwave single photon is input into the microwave single photon detector from the aforementioned microwave single photon input port, the quantum state of the superconducting qubit will not change and will remain unchanged. .

[0090] Step S406: Detect microwave single photons through the microwave single photon output port.

[0091] After the microwave single photon interacts with the superconducting quantum bit in the first resonant cavity, it will be output through the first probe and from the microwave single photon output port. At this time, the microwave single photon detector can detect the microwave single photon through the microwave single photon output port.

[0092] Optionally, applying a first control signal by controlling the read signal input port includes: applying a first microwave pulse signal by controlling the read signal input port; reading the first amplitude and first phase of the first microwave pulse signal by controlling the read signal output port; determining the first quantum state of the superconducting quantum bit based on the first amplitude and first phase; and applying the first control signal by controlling the read signal input port in response to the first quantum state being the ground state.

[0093] In one optional embodiment, a microwave single-photon detector can apply a first microwave pulse signal by controlling the readout signal input terminal. The microwave pulse signal can be output from the readout signal output port through a second resonant cavity. The detector can frequency-convert and acquire the signal at the output port, and then obtain the amplitude and phase information of the microwave pulse signal, namely the first amplitude and the first phase, by demodulation, filtering and integration. Based on the amplitude and phase information, the current quantum state of the superconducting quantum bit is determined.

[0094] In one optional embodiment, if the current quantum state of the superconducting qubit is If the detection is successful, the microwave single-photon detector can apply the first control signal mentioned above by controlling the read signal input port to detect the microwave single photon; if the current quantum state of the superconducting quantum bit is... If the above condition is met, it indicates that the probe was invalid and the first control signal will not be sent at this time.

[0095] In one optional embodiment, the microwave pulse signal can be a square wave pulse signal with a frequency of 10 GHz and a length of 400 ns.

[0096] Optionally, after detecting the microwave single photon through the microwave single photon output port, the method further includes: applying a second control signal through a control readout signal input port, wherein the second control signal is used to control the quantum state of the superconducting qubit to change to a second quantum state; applying a second microwave pulse signal through the control readout signal input port; reading the second amplitude and second phase of the second microwave pulse signal through the control readout signal output port; determining the second quantum state of the superconducting qubit based on the second amplitude and second phase; and determining whether a microwave single photon is input to the microwave single photon input port based on the second quantum state.

[0097] The aforementioned second control signal can refer to a signal used to control and change the quantum state of a superconducting quantum bit, which is the opposite of the aforementioned first control signal.

[0098] In one optional embodiment, after the microwave single-photon detection is completed and the aforementioned time window ends, the microwave single-photon detector can apply a -Y gate control signal to the superconducting quantum bit through the aforementioned control readout signal input port, so that the quantum state of the superconducting quantum bit changes from a superposition state to a second quantum state. Then, the detector can apply a second microwave pulse signal through the control readout signal input port. This signal can be output from the control readout signal output port through the second resonant cavity. At this time, the detector can frequency-convert and acquire the pulse signal at the readout signal output port, and obtain the amplitude and phase information of the new microwave pulse signal, namely the aforementioned second amplitude and second phase, through demodulation, filtering and integration. Finally, the detector can determine the current new quantum state of the superconducting quantum bit, namely the second quantum state, based on the amplitude and phase information, and determine whether a microwave single photon has been input to the microwave single-photon input terminal based on the second quantum state.

[0099] In one alternative embodiment, the second microwave pulse signal can be a Gaussian pulse signal with a signal length of 10 ns and a frequency equal to the transition frequency of the superconducting quantum bit, for example, 8.643 GHz.

[0100] Optionally, determining whether a microwave single-photon input port receives a microwave single photon includes: determining that no microwave single photon is received at the microwave single-photon input port in response to the second quantum state being the ground state; and determining that a microwave single-photon is received at the microwave single-photon input port in response to the first quantum state being the excited state.

[0101] In one optional embodiment, if the current quantum state of the superconducting qubit is This indicates that a microwave single photon was input through the aforementioned microwave single photon input port within the aforementioned time window; if the current quantum state of the superconducting quantum bit is This means that no microwave single photon was input through the aforementioned microwave single photon input port within the aforementioned time window.

[0102] Example 3

[0103] According to another aspect of the present invention, a computer-readable storage medium is also provided, the computer-readable storage medium including a stored program, wherein, when the program is executed, it controls the device where the computer-readable storage medium is located to execute the microwave single-photon detection method of the above-described method embodiments.

[0104] Example 4

[0105] According to another aspect of the present invention, a processor is also provided, which is used to run a program, wherein the program executes the microwave single-photon detection method of the above-described method embodiments.

[0106] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0107] In the above embodiments of the present invention, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0108] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual couplings, direct couplings, or communication connections may be through some interfaces; indirect couplings or communication connections between units or modules may be electrical or other forms.

[0109] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0110] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0111] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0112] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A microwave single-photon detector, characterized in that, include: The metal cavity includes a first resonant cavity and a second resonant cavity. A first probe is mounted on one side of the first resonant cavity, and a second probe and a third probe are mounted on one side of the second resonant cavity. The second probe is connected to the control readout signal input port of the microwave single-photon detector, and the third probe is connected to the control readout signal output port of the microwave single-photon detector. A multi-port device, wherein a first port of the multi-port device is connected to the microwave single-photon input port of the microwave single-photon detector, a second port of the multi-port device is connected to the first probe, and a third port of the multi-port device is connected to the microwave single-photon output port of the microwave single-photon detector; A superconducting quantum bit traverses the first resonant cavity and the second resonant cavity, wherein the superconducting quantum bit is composed of a planar capacitor and a Josephson junction, and the superconducting quantum bit is coupled to the first resonant cavity and the second resonant cavity respectively through the planar capacitor.

2. The microwave single-photon detector according to claim 1, characterized in that, The parallel plate capacitor is formed by fabricating a superconducting material thin film, and the Josephson junction is a Josephson junction with a three-layer structure of superconductor-insulator-superconductor.

3. The microwave single-photon detector according to claim 1, characterized in that, The microwave single-photon detector also includes: A substrate, extending across the first resonant cavity and the second resonant cavity, on which the superconducting quantum bits are disposed.

4. The microwave single-photon detector according to claim 3, characterized in that, The substrate is a silicon wafer or a sapphire wafer.

5. The microwave single-photon detector according to claim 1, characterized in that, The resonant frequency of the first resonant cavity is less than the resonant frequency of the second resonant cavity.

6. The microwave single-photon detector according to claim 1, characterized in that, The second probe penetrates into the second resonant cavity by a shorter length than the third probe penetrates into the second resonant cavity.

7. The microwave single-photon detector according to claim 1, characterized in that, The ambient temperature of the microwave single-photon detector is lower than the preset temperature.

8. A microwave single-photon detection method, characterized in that, The method is applied to the microwave single-photon detector according to any one of claims 1 to 7, and the method includes: A first control signal is applied through the control read signal input port, wherein the first control signal is used to control the quantum state of the superconducting quantum bit to change from the ground state to a first superposition state; A microwave single photon is input through the microwave single photon input port; The microwave single photon is detected through the microwave single photon output port.

9. The method according to claim 8, characterized in that, Applying a first control signal through the control read signal input port includes: A first microwave pulse signal is applied through the control read signal input port; The first amplitude and first phase of the first microwave pulse signal are read through the control read signal output port; Based on the first amplitude and the first phase, the first quantum state of the superconducting quantum bit is determined; In response to the first quantum state being the ground state, the first control signal is applied through the control read signal input port.

10. The method according to claim 8, characterized in that, After detecting the microwave single photon through the microwave single photon output port, the method further includes: A second control signal is applied through the control read signal input port, wherein the second control signal is used to control the quantum state of the superconducting quantum bit to change to a second quantum state; A second microwave pulse signal is applied through the control read signal input port; The second amplitude and second phase of the second microwave pulse signal are read through the control read signal output port; Based on the second amplitude and the second phase, the second quantum state of the superconducting quantum bit is determined; Based on the second quantum state, it is determined whether the microwave single photon is input into the microwave single photon input port.

11. The method according to claim 10, characterized in that, Determining whether the microwave single-photon input port receives the microwave single-photon based on the second quantum state includes: In response to the second quantum state being the ground state, it is determined that no microwave single photon is input to the microwave single photon input port; In response to the second quantum state being an excited state, the microwave single photon is determined to be input into the microwave single photon input port.

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